A device-to-device proximity service (English full name: Device to Device Proximity Service, English abbreviations: D2D ProSe) between user equipments (English full name: User Equipment, English abbreviations: UE) has become a hot topic for a Long Term Evolution (English full name: Long Term Evolution, English abbreviations: LTE) system.
Currently, there is still no perfect solution to transmitting a signal in the D2D ProSe. A possible case is that a conventional LTE mode is directly used, that is, using a dynamic scheduling mode to transmit a signal, for example, a discovery signal, on a fixed segment of time-frequency resources. However, in coverage of a macro cell, when a quantity of user equipments is relatively large, multiple user equipments need to be scheduled, so as to allocate time-frequency resources, and it is likely that real-time scheduling cannot be performed, which may cause some user equipments to wait for an excessively long time.